Tuesday, March 1, 2016

The March Sky and Tonight's Sky for March 1: Third Quarter Moon

With the month of March upon us, the
lengthening of the days will be at its most noticeable as the Sun
moves fastest near the equinox, which occurs on the 20th
of the month. Besides the rapidly shortening nights thanks to the
lengthening of the day, another dramatic loss in dark sky time will
come on the second Sunday of the month (the 13th), which
is when Daylight Savings Time returns. Needless to say, by month's
end, there will be far less opportunity for observing as nightfall
will come a lot later than it did at the start of the month. However,
at least for a short while, there will be an extended window for
morning observing with an extra hour of darkness at the start of the
day.

Cool Constellations

At
the start of March, the first order of business should be getting a
last look at the winter constellations under dark sky conditions as,
with the advent of DST, most will be low in the Southwest come
nightfall and, unless one has a good horizon, too low to observe very
well. The early-month, early-evening observing list should include
Cassiopeia,Cepheus,
Perseus,
Orion,
Canis Major,
and Canis
Minor. A few other winter constellations, including Auriga,
Taurus,
Gemini,
and the Pleiades are still reasonably well-placed, though. As Orion
was to winter, the Big
Dipper is to spring in that it is a signpost to the stars.
Starting at the Dipper, follow the arc of the Dipper to bright orange
Arcturus, alpha Bootes,
and the brightest star in the spring sky. To the left of the
kite-shaped Bootes, look for the arc of stars that is Corona,
the crown. Next, speed onto blue Spica, alpha Virgo,
and one of the brightest spring stars. Next, continue the curve to
trapezoidal constellation Corvus,
the crow. Finally, conclude in dim Crater the cup. Moving higher in
the sky, zodiac constellations Cancer
and Leo
are well-placed as well. Speaking of Cancer, look just below the
cosmic crab for a distinct ring of stars, the head of Hydra, the
sky's biggest constellation, which snakes (sorry) through over 120
degrees of sky. For those who like to stay up late (or get up
extremely early), there's mythological strongman Hercules
and the Summer Triangle high overhead and, to the South, Ophiuchus,
Serpens, and Scorpius

Planetary
Perceptions

On
the planet front, you'll need to be an early bird to catch 4 of the 5
naked eye planets. The one exception: Jupiter,
which reaches opposition on March 8. What does this mean? As seen
from Earth, Jupiter is opposite the Sun in the sky, meaning that
Jupiter is up all night from sunset to sunrise. Moving into the
night, Mars
is next to break the horizon, albeit in middle of the night, followed
by Saturn.
An item of note: Mars is clearly converging with Saturn as Saturn was
rising about 2 hours after the Red Planet at the start of March but,
by month's end, they will be rising within 45 minutes of each other.
As an interesting note, the Moon will make a pair of close passes of
these two planets, on the mornings of the first and 29th.
Try and see both events as one will clearly be able to see how much
closer the planets are with the Moon in the picture. Moving to the
immediate predawn sky, Venus
hangs very close to the predawn Eastern horizon all month. As for
speedy Mercury,
it will disappear from the morning sky early month before making a
sudden reappearance as an evening object the last week of March as it
heads toward its best evening appearance of the year in mid April.
Last but not least, there's a true Young Moon (under 24 hours past
New) visible at dusk on the 9th.

Tonight's
Sky for March 1: Third Quarter Moon

Today,
the Moon,
second brightest object in the sky, has reached the Third Quarter
phase, which means that it is exactly 270 degrees around its orbit of
Earth.

As for lunar mechanics, the Moon is always half lit.
The reason we don't always see it as such is thanks to orientation in
relation to us. Right now, with the Moon at a 90 degree angle
relative to the Earth and Sun, we see the Moon as half lit and half
dark, leading to the popular, erroneous phrase 'half Moon.'

After
today, we will see less and less of the Moon as its lit side turns
more away from us and heads toward a new lunar cycle.